Orientable support heads of the type indicated are typically used in connection with stands, tripods or other supports which are known in the technical sector being referred to in order to support optical or video-photographic equipment in one or more preselected spatial orientations.
Those heads are typically provided with one or more articulation joints, for example, of the spherical or cylindrical type, in order to vary the positioning of the equipment supported by the head with respect to the support to which the head is fixed.
Generally, the conventional support heads are provided with a locking device which can be actuated selectively in order to lock the articulation in a desired configuration and in order to release the articulation in order to allow the positioning of the equipment in a new configuration, respectively.
WO2013/117538 describes a support head comprising a cylindrical member which is provided with an internal cavity to rotatably receive a ball and a locking device which can be actuated in order to clamp the ball against the cylindrical member.
The ball is supported on a sliding ring which is in turn supported on a pressure ring.
The locking device is actuated by means of a handle which is arranged externally with respect to the cylindrical member and comprises a threaded shaft, on which there are positioned two threaded blocks which are provided with an inclined surface which is directed towards the ball and which is intended to abut an additional inclined surface of the pressure ring. By the threaded shaft being rotated by means of the handle, the threaded blocks are moved relative to each other on the shaft itself, and the inclined surfaces thereof slide against the inclined surface of the pressure ring so as to lift it by clamping the ball between the pressure ring and an abutment ring or, vice versa, so as to allow a lowering of the pressure ring by making the ball free to rotate in the cavity.
A drawback of that locking system is that it is not very durable because the sliding surfaces become worn over time.
That drawback is particularly evident in the case of heads having substantial dimensions and weight.
Another drawback of that locking system is that it has a low level of efficiency as a result of the losses owing to sliding friction between the rubbing components during the locking/unlocking.
The losses owing to friction increase the rotation which has to be imposed on the handle in order to obtain the locking/unlocking and the force required by the user in order to actuate the locking system.